Filter and method for construction of a filter

ABSTRACT

A large vault or tank receives the runoff water to be cleaned. There are one or more small tanks in the large tank (vault). Each small tank is inverted and receives water at its open lower end, from the large tank. The water entering the small tank rises, as the water level in the large tank rises, and flows upward through a filter. When the water level rises above the top of the filter it enters an outlet tube or pipe and then flows downwardly along the center-line of the filter. A float, a valve and a check valve may cause the system to function as a siphon and feed the filtered clean water to an outlet. Alternatively the siphoning effect will occur if the inside diameter of said outlet tube is small enough to form a partial vacuum.

RELATED APPLICATIONS

This application is a divisional of and claims the benefit of ourco-pending application Ser. No. 11/522,150; filed: Sep. 16, 2006 andpublished as publication number 2007/0023352 on Feb. 1, 2007 andscheduled to issue as U.S. Pat. No. 7,708,149 on May 4, 2010; which isclaims the benefit of our prior co-pending U.S. Provisional applicationSer. No. 60/718,717, filed Sep. 20, 2005 and a continuation-in-part ofprior co-pending application Ser. No. 11/030,939 filed Jan. 5, 2005 ofco-inventor Thomas E. Pank. We also claim the benefit of co-inventorPank's provisional 60/543,942 filed Feb. 12, 2004.

BACKGROUND OF THE INVENTION

This invention was developed by BaySaver Technologies Inc. (BaySaver) amanufacturer of stormwater pollution controls based in Maryland.BaySaver is licensed under U.S. patents on several different physicalseparators, including patents U.S. Pat. Nos. 5,746,911 and 6,264,835,both titled “Apparatus for separating a heavy fluid from a light fluid.”While physical separators accomplish a great deal and are an importantfactor in environmental protection, they do not remove dissolvedcontaminants, nor do they remove sediment particles in the fine silt andclay size range.

Filtration is a proven method of removing dissolved and very fineimpurities from a fluid. The most commonly used filter in the stormwaterindustry is a depth filter. A depth filter uses a media (sand, forexample) that the fluid must pass through. The removal is achieved by acombination of two mechanisms: transport and attachment. In a sandfilter, the individual grains obstruct the flow of water, forcing thefluid to take a more tortuous path through the filter. When thishappens, the fluid comes into contact with far more of the media than itwould if it were to flow straight through the filter. The fluid, alongwith the impurities to be removed, is in contact with the individualgrains of sand or other filter media. Bringing the contaminants intocontact with the filter media is the first stage—the contaminants aretransported into contact with the filter media.

In order to remove the pollutants from the fluid, the media must havesome way of capturing and retaining the contaminant. This can beaccomplished in a number of ways, from chemical bonding on reactivemedia to simple sedimentation in the interstices between the mediacomponents. When designed carefully, media filtration is capable ofremoving large pollutant loads from influent fluid streams. The presentinvention can be used to remove fine sediments, and other entrainedpollutants such as oils and grease, and dissolved contaminants fromrunoff streams. It can also be used to reduce turbidity in the sameapplications.

The selection of filter media can depend on many factors, including thetype of contaminants targeted for removal, the desired flow ratesthrough the filter, the cost and weight of the media, and other factors.While filtration is a proven technology in fields like wastewatertreatment, drinking water treatment and industrial processes, it isrelatively new in the field of stormwater treatment.

One of the challenges of stormwater management is dealing with thehighly variable runoff flow rates, that result from storms. Instormwater applications, treatment devices are subjected to widelyvarying flow rates, from very slow trickles to the runoff resulting fromtorrential downpours. To accommodate these variations, many stormwatertreatment devices are designed with an internal or external bypass. Thebypass allows flows in excess of the intended treatment capacity to passthrough the unit untreated, while continuing to treat flows within theintended range. This is a viable technology because of the “first flush”effect in stormwater runoff. During the beginning of a storm event, a“flush” of contaminants is carried off of a site with the first bit ofrunoff. This flush includes the pollutants that have collected on thatsite since the last storm, and comprises the majority of the pollutionload from each storm event. If the first flush is treated adequately, amajority of the potential contaminants will be removed during thattreatment and the subsequent bypass flows during extreme storms will notcontain the same heavy pollutant loads.

SUMMARY OF THE INVENTION

This invention relates broadly to a system for filtering a fluid,however one specific application of the invention is to remove smallparticles, including dissolved contaminants, from runoff water. Intreating runoff water it is desirable, but not necessary, to firstremove the large particles of contaminants by gravity separation (seeU.S. Pat. Nos. 5,746,911 and/or 6,264,835 by Thomas E. Pank).Thereafter, the runoff water is fed to the present invention (FIGS. 1 to12 incl.) for removal of small particles and/or dissolved contaminants.

The present invention employs a large vault or tank for receiving therunoff water. There are one or more small tanks in the large tank(vault). Each small tank is inverted and receives water, from the largetank, at its open lower end. The water entering the small tank rises, asthe water level in the large tank rises, and flows upward through afilter. When the water level rises above the top of the filter it entersan outlet tube or pipe and then flows downwardly along the center-lineof the filter. A float, a valve and a check valve may cause the systemto function as a siphon and feed the filtered clean water to an outlet.Alternatively the siphoning effect will occur if the inside diameter ofsaid outlet tube is small enough to form a partial vacuum.

While my overall device is primarily for use in cleaning runoff water,various features of the invention have widespread application in thefield of filtering; hence many of the claims are not limited to cleaningrunoff water.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the unnrolled layered filter.

FIG. 2 is an elevation view of the unrolled layered filter, taken alongline 2-2 as indicated in FIG. 1.

FIG. 3 is a plan view of the rolled filter cartridge.

FIG. 4 is a cross section of the assembled filter taken along line 4-4in FIG. 3.

FIG. 5 is a cross section of a single “lap” of the layered filter.

FIG. 6 is a plan view of one form of the invention.

FIG. 7 is a cross section of the form of the invention shown in FIGS.1-6, taken along line 7-7 in FIG. 6.

FIG. 8 is a cross section of the form of the invention shown in FIGS.1-6, taken along line 8-8 in FIG. 6.

FIG. 9 is one form of the output system of the invention.

FIG. 10 shows a cross section of the filter cartridge with a float valveto control the effuent flow.

FIGS. 11 and 12 show cross sections of inlet layer 7 and outlet layer 9,respectively.

DETAILED DESCRIPTION OF THE INVENTION

The invention is a modular filter system for stormwater runofftreatment. The filter itself comprises several layers of drainagematerial and filter material as described in the copending applicationof Thomas E. Pank, which has been published, see Publication No. U.S.2005-0178719A-2 dated Aug. 18, 2005.

The complete invention comprises a filter cartridge 21 that is placed ina housing, or large tank, 19. Contaminated fluid enters the housinginput tank 19 through an inlet means 17 and accumulates within saidhousing 19. The fluid may be contaminated with solid particles,undesirable gases, dissolved chemicals, or other pollutants. Within thehousing 19, the contaminated fluid enters the filter cartridge 21 and isdirected through the filter media 11 contained in said cartridge 21 toremove contaminants from said fluid. Said fluid displaces air withinsaid cartridge 21 through a check valve 14, establishing a siphoneffect. The siphon continues to pull fluid from said housing throughsaid filter cartridge until the siphon is broken and air is reintroducedinto the filter cartridge.

The method of constructing the invention is also a part of thisapplication. The filter cartridge is constructed by rolling a layeredfilter around a center drain pipe. FIG. 1 shows a plan view of theunrolled filter layer. The filter layer consists of an inlet layer 7open at its bottom, which is in communication with filter media layer 8.If necessary, inlet layer 7 may be separated from the filter media 8 bypermeable barrier 11. On the other side of said filter media, outletmeans 9 is open at the top to allow fluid to exit the layer by flowingupwards. On one end of the unrolled layer, vertical drain pipe 4 isplaced.

There are numerous forms that the layers 7, 8 and 9 may take and we willset forth two of those forms.

In one of said forms: (a) the strips 7 and 9 may be made ofpolypropylene cloth and have a thickness of 0.3 inches and a width of 30inches; and (b) the filter strip 8 is made of high grade geotextilefabric, has a thickness of 0.3 inches and a width of 30 inches.

Another form that the layers 7, 8 and 9 may take is described in thenext four paragraphs.

Inlet layer 7 and outlet layer 9 may be defined by permeable materialthat maintains the shape of said layers so that said layers are empty.In one form of the invention, however, said layers comprise two separateplastic materials: two layers of a relatively rigid high densitypolyethylene (HDPE) drainage material that provides structure to saidlayers and an ethyl vinyl acetate (EVA) material fills the space betweensaid layers. In the current mode of that invention, said HDPE materialis Poly-flex (a registered trademark). Drainage Net, and said interiorfilter material is Matala.™.

Poly-flex Drainage Net is a high-density polyethylene product between0.25 and 0.50 inches thick, consisting of two sides. Each side has oneseries of ridges 31 that run parallel to each other and are arranged ata 45 angle. Said ridges allow water to flow along said material, evenwhen said material is placed directly against a solid surface. Thematerial can be rolled into a spiral in only one direction at time dueto its design. When rolled, the grid develops limited rigidityperpendicular to the direction of the roll, thereby lending itself tocreating a vertical spiral roll with structural integrity. Thisintegrity also provides stability for the loose media rolled in thefilter. In the present mode of this invention, inlet layer 7 and outletlayer 9 are each defined by two layers of Poly-flex Drainage Net.

Matala mat is placed between the two layers of Poly-flex Drainage Netthat define inlet layer 7 and outlet layer 9. Matala is a proprietarymaterial developed using the plastic EVA, which is extruded from nozzlesto form spaghetti-like strands that adhere to one another. Said strandscreate a matrix with large amounts of open void space, through whichwater can flow freely. Because of the properties of EVA, Matala mats areboth flexible and compressible, allowing them to be wrapped in a spiralbetween layers of Poly-flex Drainage Net. The mats used in the presentinvention vary in thickness between ¾ of an inch and 11/2 inches.

FIGS. 11 and 12 show cross sections of inlet layer 7 and outlet layer 9,respectively. In FIG. 11, inlet layer 7 is open at its bottom to allowwater to flow upwards into said layer. The sides of inlet layer 7 aredefined by Poly-flex Drainage Net 29, which features drainage ridges 30.Matala mat 31 is placed within the open space defined by drainage net29. In FIG. 12, outlet layer 9 is open at its top to allow water to flowupwards out of said layer. The sides of outlet layer 9 are again definedby Poly-flex Drainage Net 29, which features drainage ridges 30. Matalamat 31 is again placed within the open spaces defined by drainage net29.

FIG. 2 shows an elevation view of the unrolled layered filter, with thetop 1 and bottom 2 indicated. The layered filter is significantly longerthan it is wide, and is flexible enough to be rolled around itself. Thefilter is constructed by taking a free end 3 of the unrolled filter andtightly wrapping that end around the drain 4 indicated in FIGS. 1 and 2.The unrolled filter must be long enough for the free end 3 to make atleast one complete lap around the center drain 4, and preferably is manytimes longer to provide additional filtration capacity. The resultingcartridge is then oriented so that the top 1 and bottom 2 are in thecorrect positions. A plan view of the partially constructed filtercartridge is shown in FIG. 3.

Outer walls 12 are affixed to the rolled filter cartridge to contain therolled layers in place. In conjunction with ceiling 13, the outer walls12 form a space 5 at the top of the interior of said filter cartridge,as shown in FIG. 4. FIG. 4 shows a cross section of the completed filtercartridge, taken along line 4-4 as indicated in FIG. 3. A check valve 14is located in ceiling 13. Check valve 14 allows air to escape from space5 when said air is displaced by the fluid to be filtered, and preventsair from reentering space 5 through said valve. The seams 6 between therolled layers are sealed to prevent the fluid from flowing between thelayers instead of through the filter media. Vertical drain pipe 4 flowsdownward from open space 5. Flow control 10 restricts the flow ratethrough vertical drain pipe 4 using an orifice, a valve, or other flowcontrol means. Below flow control means 10, the horizontal outlet pipe20 directs effluent flow away from the filter cartridge.

During operation, each “lap” around the centerline functions in the sameway. FIG. 5 is a cross section of a single “lap,” along line 5-5 asshown in FIG. 1. The cross section is thin relative to its length andwidth so that it can be rolled. It is shown in FIG. 5 verticallyoriented, in the same orientation it has in the complete invention. Each“lap” consists of three layers: an inlet layer 7, the filter media 8,and an outlet layer 9. The inlet layer is open at its bottom and closedat its top, and allows water to enter the filter through opening 15. Thecenter layer contains the filter media 8, and may be held in place by apermeable barrier 11 if required, through which the water can flow at afaster rate than it can flow through the filter media. The filter media8 may be sand or another filter media selected specifically for thetypes of contaminants anticipated in the influent fluid. When the filtermedia is of indeterminate shape and needs to be contained, permeablebarrier 11 holds it in place; with some choices of media (cloth, forexample), permeable barrier 11 is unnecessary. The third layer, theoutlet layer 9, is separated from the filter media by permeable barrier11. Outlet layer 9 is closed at its bottom to prevent entry ofcontaminated water and has opening 16 at its top to allow the treatedfluid to flow out of the filter unit and into open space 5.

In the complete invention, one or more of the filter cartridges arehoused in a single large structure such as large tank 19 as shown inFIG. 6. Inlet means 17 penetrates through the wall 18 of the mainstructure 19 and discharges the fluid directly into the housingstructure. One or more filter cartridges 21 are placed in the housingstructure. The discharge pipes 20 from said filter cartridge(s) jointogether and penetrate the wall of the housing structure. Said dischargepipes 20 direct treated effluent to the invention outfall (not shown).

FIG. 7 shows a cross section of the complete invention along line 7-7 asshown in FIG. 6. Said filter cartridge discharges treated fluid throughflow restriction 10 and into discharge conveyance 20. Dischargeconveyance 20 penetrates the wall of the housing structure 19 at joint22. Because joint 22 is under pressure during normal operation, joint 22must be sealed.

FIG. 9 shows a cross section of the filter device, including the flowrestriction 24 in the vertical effluent drain pipe. Flow restriction 24controls the rate of fluid flow out of the cartridge in order tomaintain a siphon during normal operation.

FIG. 10 shows an alternative flow control that may be used in place offlow restriction 24. FIG. 10 shows a float valve assembly that comprisesfloat 25, which is connected to ball 27 by rod 26. Ball 27 is seated invalve seat 28 such that, when seated, said ball does not allow flow topass through said float valve assembly.

OPERATION OF THE INVENTION

Contaminated fluid enters the invention through inlet means 17. Thefluid flows from inlet means 17 and into housing structure 19. Housingstructure 19 is in communication with the cartridge inlet layer 7 ineach lap of the rolled filter cartridge. The contaminated fluid flowsupwards from the housing structure 19 into cartridge inlet layer 7through openings 15. In the cartridge inlet layer 7, the fluid makes a90 degree turn and flows through permeable barrier 11 (if present) andinto the filter media 8. The fluid flows through the filter media 8,where the contaminants are removed by the media, passes throughpermeable barrier 11 (if present), and into the fluid outlet layer 9. Inthe fluid outlet layer 9, the fluid once again makes a 90 degree turnand flows upward through openings 16 into space 5. From space 5, thetreated fluid flows downward through drain 4 towards flow restriction10.

When the contaminated fluid flow rate into the filter cartridge exceedsthe discharge flow rate allowed by flow restriction 10, said fluiddisplaces the air within space 5. Said air is evacuated from space 5through check valve 14. Once vertical drain 4 is filled with fluid, asiphon is established. This siphon continues to pull contaminated fluidinto the filter cartridge as long as the fluid level within housingstructure 19 is high enough to prevent air from entering the filtercartridge.

Treated effluent fluid flows through restriction 10 and into horizontalconveyance 20. Horizontal conveyance 20 carries treated fluid throughhousing wall 18 and to the outfall of the invention.

Flow restriction 10, shown in greater detail in FIG. 9, can be replacedby the float valve assembly shown in FIG. 10. Said float valve assemblycomprises float 25, which is connected to ball 27 by rod 26. When fluidfirst enters vertical drain pipe 4, ball 27 is seated in valve seat 28,preventing fluid from flowing downward out of the filter cartridge. Asthe fluid level within said drain pipe rises float 25 is pushed upwardsby buoyant forces. When said float rises, it brings with it ball 27,creating an opening between ball 27 and valve seat 28. Fluid flowsthrough said opening and out of the filter cartridge.

1. The method of making and using a system for filtering a liquid fluidcomprising: providing a tube, said tube having an inlet, providing alayer of flexible filtering material, passing said material around saidtube for at least 360 degrees to form a lap, and guiding the fluid to befiltered through said material and thereafter to said inlet so that thefiltered liquid fluid is discharged through said tube.
 2. The method ofmaking and using a filter as defined in claim 1, wherein said step ofguiding the liquid fluid to be filtered through said material andthereafter through said tube in series comprises passing the fluid to befiltered upwardly, against the force of gravity, through said materialand downwardly, with the force of gravity, through said tube.
 3. Afilter for filtering a liquid fluid, comprising: a tube having an inlet,a layer of flexible filtering material, said layer forming a woundfilter element in which the first lap of the wound filter elementextends around said tube for at least 360 degrees, and a fluid guidingsystem for guiding the fluid to be filtered through said filteringmaterial and thereafter to said inlet so that the filtered fluid isdischarged through said tube.
 4. A filter for filtering a fluid asdefined in claim 3, in which said fluid guiding system comprises anenclosure for guiding the fluid to be filtered through said filteringmaterial and then to said inlet, said tube having an outlet at a lowerlevel than said inlet so that fluid fed to said inlet flows out saidoutlet due to gravity.